"Mailing seals for use with both laser and inkjet printers. Use seals with tri-fold brochures to eliminate the need to stuff envelopes. Perforation allows for easy application. Customize your promotional mailings with bright graphics and text without paying for expensive commercially printed seals. Follows USPS regulations for bulk mail. Save up to 15% on mailings with bulk rates. Check www.usps.com for details. 3 1/3"" x 4"" seals are address labels, return address labels and mailing seals all in one. "